Electronic regenerative repeater



Aug. 20, 1946. M. MoRRlsoN ELECTRONIC REGENERATIVE 'REPETER Fuga dst. 2:5, 1943 2 Sheets-Sheep 1 ug.- 20,1946.' l A MMQRRlsQN l l 2,406,096

F/////Y ,If/ f W/ -7// ELECTRONIC REGENERATIVE REPEATER u Filed oct. 25.1943- *a Shepfcs-sneet 2 'a b' c [d -fhg lower rlaudio range.

i, ed'amental j- :frequencyj of the iwhich means that there are K'. 4 multi-vibrator.

tween cathode I andground-lead "sistor is-low enough to prevent the 4odefl isl connected to vibrator 2 will start into operation instantly, pro- Yducing a'fundamental cycle lof the 'frequencyvsourcel.l v Y 10'.'5cycles'of`source r I for=asingle'half-period of order be furnished with an accuracy upto one part in one million, for frequencies within the The frequency of source I will be setv at, forV the present embodiment, a frequency of 472.5 cycles per second. The `usefulness of this value in the present embodiment will be hereinafter pointed out.

The circuit enclosed within the dotted area 2 represents a1 multi-Vibrator circuit Well known in the art, y'andi thefconstantffrequency source I injects asynchronirzing'voltage into the `multivibrator circuit, which, as is well known in Y,the art, will, under proper conditions, X thefrequency of the multi-vibrator circuit ata definite I15V sub-multiple of the frequencyof source I.

Y this lag in phase not exceed 10% of the half-period value, as will be understood by those skilled in the art.

Multi-vibrator 2 is constructed tooperate atav4 sub-multiple frequency of the frequency ofv source,

I, represented by the 21st which means an operating vibrator 2,V of 22.5 cycles pe-r second for the fundamental frequency represented sub-multiple thereof,

Y 10.5 constant-fre- Y fluency-source cycles for each half-cycle of the The usefulness of this 10.5 cycle Y A constant frequency source'ratio to one-halfcycle 'of themulti-vibrator 2 will be hereinafter pointed f ouh y y f Y The multi-vibrator circuit is provided with two z tub'es, 3 Vand 4, and thislmulti-vibrator circuit 1 i .differs from the `cornmonform of multi-vibrator L circuit only necessarily in 'respect to the cathode grid circuit of tube 1. resistor 6 connected'to the cathode 'I and to the plate of th'gaseous l connected to ground-lead Y9.. The ohmic value i of resistor 6 is too i closed within the vibrator, when the plate current ofV tube 4 is Alimited by said resistor, and said resistor has sub- 4, which is provided with a triode 8, having its cathode high to permit the circuit enarea 2, to function as a multis'tantially the same effect as an-open circuit be- 9, but Ysaid repotentiall difference between said cathode' and said groundlead, ,from drifting to different and indenite values, when multi-Vibrator-2, is not oscillating. yWhen gaseous triode 8 is in anon-conducting state, the cathode 1-is` substantially in effect y disconnected from theA ground-lead 9,V under if .which conditions only theresistor 6 is interposed between cathode 'I andground-lead 9,y and said resistor being suciently high to produce in effect cut-'off of theV plate l'current inr tube 4, so that is conducting no current trand tube3 is conducting the normal f 1 amount of current for the plate under normal multi-vibrator operation.

under theseconditions tubey 4 voltage employed t If source I is under proper operationand cathground-lead 9, the multiy Y y frequencybetween leads II andv I2Y of 22,5 cycles'per second withv a funclosing' ofv cathode 'I onto lead 9A of ja' maximum 2,; since the multi-vibrator '2 will lock in with4 multi-vibrator 2,

` y not to' exceed 10% of the* half-period of fthe frequency of the multi-vibratorY by a 'dot anda v space. This means; that :the vconstant frequency y f source operates at 'thea21st harmonic yof the fun- The means of, and method for, closing cathode 'I onto lead 9 by the employment of gaseous triode 8 willV be hereinafter pointed out.

It is Well known in the art that the ability of l In the'present invention, it is desirable to not only maintain an unvarying performance in the multi-vibrator circuit, but its wave-form is desirably-maintained under varying conditions of Y c Vemployment. frequency for--mu1ti--" This may be accomplished in one ofl several way one of which is illustrated diagrammatically inthe dotted area I 3, which forms a; highly practicalarrangement.'V 'Twol'tubes VI4 and I5 l'i'aw'ev` the control Y respectively'to; the'fplates of Vtubes @and 4, and

l. 'fthe plate'sof tubes ti-vibrator operation 'I4 'andVV I 5A are connected together and thence connected to the load'center I6 of the multi-Vibrator circuit2. This arrangement provides sucient grid plate bias 'voltage fromvmulti-vibrator circuit 2 to cutoff plate cur- I5 in the presence of multirent in tubes I4 and vibrator operation.

Those skilled in theV art appreciate that in multhe Voltage is developed rst between lead-s I I and point I E, with substantially no Voltage between point I 6 and lead I2, for one half-period of operation of multi-vibrator 2, and the conditions are reversed for ,the

- other half-period of operation; that is, voltages develop between'lead I2gand point* I6 with substantially no voltage betweenlead I I and point I6.

. Y Under this condition of operation,tubes I4 and I 5, under the potential of plate battery'I'Land a properly closed circuit, produce in the load I8 an accurate 'replica ofthe voltage wave-form produced by multi-'vibrator 2 and without Y Since the operation of` tubes I4 andAIS-is such that no appreciable load is taken from multi- -vibrator 2, under any condition of operation of these tubes, that is, whether plate current is pres- Vent or not in said tubes, the shape A of the grid control voltage of these said tubes, will follow .fthe shape of the voltage, in the multi-vibrator j circuit 2 always, ycuits I4 and currents of said tubes willassume so-called square r wave-forms.

" tive outline, as the case may zbe. V

and Lifand when the tube cir- I'5 are properly closed, the plate Tubes I4v'and: I5, beinga push-pull circuit, or in eifectthe reverse of this which may be referred to as a pull-'push circuit, the Waveform in load resistor I8 is, ofcourse, a rectificationof the wave-form in multi-vibrator 2 and, therefore, always has a positive or always a nega- ",With multi-vibrator 2 in operation, the Iform of the voltage acrossload resistor I8, which representst'he form of vVoltage across the output circuit of the repeater and' so designated ir Fig. 1,

willfollow the rectied outline of the lobes of multi-vibrator;'L 7 only whenjthe cathode circuits of tubes I4 and I5 are closed forv an entire halfperiod of operation of the multi-vibrator'circuit.

not lne-more than the `time represented yby one Y Since there are Asents one means ,I4 and I5referred to above, and this means comprises gaseous triodes 20 and 2| The circuit enclosed in dotted2 area I9 repre- `of closing the circuits o'f tubes so connected into the cathode circuits of tubes I4 and I5, as-to closev thesesaid cathode circuits' when the said including the circuits loadingV grids thereof connectedY distortion.

Y Vsuliciently to permit' ofV these tubes upon the appearanceofthe operating Vplatevol-tage.Y i

Y than period. curve C produces no ffi 1 '2,406,096

stant a when the input voltage, Fig. '1, fhas reduced the bias Voltage value of tubes and 20 gaseous conduction in The value ofthe resistance of Ivis too high to permit the two multi-vibrator circuits to operate as such, but is sucienttoinsurea definite plate,

voltage across thetube kIi andtherefore at the constructed. Frequency source I, being in operation, multi-vibrator 2 locks in With'it, not more of a single dot period behind the phase instant a, and multi-'vibrator 2 continuesin operation as long as the cathode 'I is effectivelyv connected to the ground-lead 9.

Y Referring to Fig.`2`, curveC represents the volt- 1 V,age output of multi-vibrator 2 and afrectication of "this curveY represents the line output' voltage which may be biased if and when desired,

asindicated by the connection at point 29, Fig. V1. It will be appreciated that the plate voltage impressed upon tube 8 by multi-vibrator circuit 2 is only present for each .certain half` cycle thereof Yand means is provided for maintaining gaseous conductionin'this tube for the necessary duration of the operation cycle. This is accomplished by multi-vibrator 24, the wave-form of which is indicated by curve D, Fig. 2, and

which provides plate current for tube 8 for the three half cycles of six units of the repeater operation during wh-chtube 4 is idle and allows tube 8 to be restored to its non-conducting status at the ends of the code cycle. V Y

Referring to Fig. 2, reduction of voltage in curve B, between the time intervals a-b, operates to utilize the lobe of multi-vibrator 2 curve C for that period, to produce the line currentV curve E during the same period. There being no reduction in line voltage for the period b-c for the curve B, the multi-vibrator lobe for that line voltage, as shown in curve E. ,y

In the case Where the reduction in line voltage lasts Yfor two units as'indicated between the lines c-e `curve B, two consecutive lobes of the multivibrator shown along curve C is caused'to produce two unitsfof line signalcurrent Yfor that period, as shown along curve E.

If une biasis used, the signals shown amg curve E can be restored to the equivalent closed circuit form indicated along curvefF, asis fully understoodfby those skilled in the art.

time instant a, the cathodes -of tubes 4 vand 25 are effectively connected to the ground-lead 9y 'and the two multi-vibrators start in operation VVThe curve 'along abscissa A is Yassumed to be sent out at a conventional nrate of A words per minute which lixes combined frequency of a dot and a space at 22.5 cycles per second, making `the dot or markingperiod equal to-,afhalf Va period of the multi-vibrator 2.

The penodof'mruu-vibrator 24 ,is fsughuy lessl t than: 7.42 units, or'less V.than .the distance a-h, ras shown along curve D, Fig. 2, one lobe having six units of duration, as illustrated ybythe curve for thev embodiment herein given. vThe'length-of duration of. the long lobe of curve D depends upon the use to which itis to be putin the particular system incorporating' the invention. In a continuous distributor system Vemploying a ve unit code, the duration of the 1ong 'lobe wouId Yinput circuit identified in reception of any character signal current, normal Yamount to fewer units, in somecases less than live units, in other cases more thanrve units.

A -detailed operation of the device for the regeneration of the character D, shown ln graph line current is flowi g through the input resistor 3I'. Tubes 20 and 2 I, are both in a non-conductjing electricalstate, due to their previous `history lof operation and to the grid bias` supplied by resistor 3 I. Y Y

Tube 8 is in a non-conducting electrical state, due likewise, to theV grid bias supplied byjresistor 3|. Under this-condition, the plate circuits vof tubes 4 and 25 are substantially open-circuited andtubes 3 and 2B are conducting their normal plate currents. Under these conditions, the plate current of tube 26Vservesrno operatively useful function. The `plate current of tube 3, through its associated plate resistor, provides plate current cutol bias for tube I4, which rmaintains tube I4 in an electrically non-conducting state. The absence of plate current in tube4 causes an absence of grid bias in tube I5, but in Vview of Vtube 2I having been left in an electrically nonconducting state, the circuit ofV battery through tube 2|, resistor IB, is effectively open. Likewise the circuit of battery I'I, through tube 20, through tube I4 and through resistor I 8, is effectively Open. Normal output line current is supplied by bias provided by battery I1. Thus with a normal steady current in the input circuit, a normal steady current is repeated in the output circuit. This status corresponds tothe zero time position of the curve shown in graph B. Y 1

When the signal. wave shown in graph B arrives at the time position a, the grid bias of tube 8 is lowered, due 15o the reduction vin signal current. to a value which causes tube 8 to acquire an, electrically conducting state.

condition to start its normal operation immedi-` ately upon completing the multi-vibrator circuit, by causing tube 8 to `become electrically conducting.

It may be well to mention at this point, .that properly designed multi-vibrators, unlike capacitor-reactor oscillators, are set into normal operation under conditions set forth above, instantaneously with .the establishment of the normal circuit thereof; so that at the instant that tube 8 forms a closed circuit for multi-vibrator 2, multi-vibrator is set into normal operation' an-d it locks in with the-constant frequency source at the iirstV half cycle of the proper'polarity that coincides withV the'V normal grid voltage of the said multi-vibrator, as is well vunderstood in the Y Vart relating to this apparatus.

multi-vibrator 2, andtube 25 was ina non- I 'I,Y through tube I5 Vand through plate current of tube sation of plate current in tube 3, tube I4 has its Go conducting .m tube 4Q; so thatfull-ren@tu-heil becamelelec :tric-:allyl conducting', 1-bQtlrm1-1ltivibrators -2 and 24, were instantaneouslyset intonormal cperaticn.-

Multi-vihraterl l producesawoltage wave-form. in accordance-Wittig graph-1G so vlo'ng as the -tube 8f is electricallyconducting-s and, likewise, multivibratorr- .4 produces 'a wave-form accordance with graphA D nse@` long- Aastube /8 @remains in? -an multi-vibrator-` 7 2 l is to maintain j tubeA 1 8 fin an electrically f conducting state'.- for a duration offw approximately =sixhalf cycles ofll multi-vibratorV f 2, by maintainingcurrent"throughtube8, for` t 4 is not-15 the periods .foftime-during whichl ytube Y passingplate current; namely, during everyfothery half cycle', and then*permittingtube'8 to fbe-*f come electrically nonTconducti-ng;bywremoving the plate* current ,caused bylfmultif-vibrator; 24

at the end of this period, since at thisy instantie() of time, there isfno platecurrent-1in :tube 4-1-tov maintainelectricalvconductivityin tube 8 eitherw In other Words, vat-the end.y of six half .cycles of operationf of `multivibratorv2 and at the rends "of:y the same duration. -offtime' in nmulti-vibrator 24;v there is-r1ol lcurrent availableV from 'either fmul-ti'- vibratory to maintain `',electricalfy conductivity` win-wV tube 8 Jand'lthereforefboth multi-'vibrators'1 are I f returned @t0-1.. thef initial scribed ffor-themn These sught -fphase shiftsl 'between @the input anaffthe output- 3circuit-fare :ignoredfsin'fthisz description since theycanibe hmade' asrsmalr asldesirable'rfandi may berconstant-.ffor anyrprop'er tem employingitrsfinvention;

Return 'now' `tto th'e Y`"signal graph `Beat*therltime finstant".a;f:tube"8 :1i electrically'fconductirg'iand multi-vibrator 24 start-into operationfin accordancewitlr'graphs. C and D -fiff i The instr ti that)v tube? 81"- sets therr multi-vie brators "into operation-grobe 4 dravvsfnornialfplate currentyiproducing:due: tof its l'plateiir'e'sistor sufcient. 'gridchiasc-for*v current. The plate current of tube 4 is represented bytli'srstfha'ltlcycllofgraph C, and under conditions of multi-vibrator operation, the

3 ceases. With the cesplate-grid bias removed, and Idue to the reduction in signal current at the instant a in graph B, the plate voltage applied to tube 28 by the removal of grid bias from tube I4, produces plate meramente egrgstatustf d necessary cutoff voltage-fr-. the electrically.@conducting state; f The; function of ,lQ

inoperativeestatus j detwofcomplete 'cycles ofV 30 operation for: these multi-vibrators;V isperformedfl fcorresponding period in graph 1B:t

When theasignal current Vofi-graplrr- .B vrhas tube 2-I;--butsincethe gridzbi-asffoftube ZIffhas f risen above the cutoff value for the normal;plateV ,Si voltage'no current flows through resistcrlrln ff'the circuit including--tubesn-Zgand ,Ii-*forthe next fhalf period hoiethepV multi-vibratorf-g. hence-: ,lthe output 'circuit fre-turns to t its` 1normal :currentfdue v4to biasgf as-previous1yqldescribed an ascii-lusL A Sei-n ana'electrically '-corrductingg; stateyinnthe fabsenceiofaplate r`"current-fin` tube e4; during'the-2ndel 4thfza`nd-6th 'half cycles 1of operation "fof multivibrator-YZ ,zas

has beenpreviously'describedr'r1f f-fi`v g 'j WhenA the.' timeV instant c graph Bpis: reachedf the previouls'statu'sofi operatiorris exa'ctlyfae 'de'- with that described 'he succeedingfaaircycif en scribedbeginhingflt the time instant ufr-11d co` timingY themen thefftimef period 1t-9b ff rnc We have' the''distortdmignal jcurrnt "for Athe period 'of-six"halficyclesfrom a'to' "y, graphfB, regenerated'jnt the forni "shownf in graph A" for," the saine' period cri time;'Howevedcring' the electrically conducting condition and this continued up to the time instant indicated by g in the graphs, and at this instant multi-vibrator 24- reverses its polarity and tube 25 ceases to supply `conduction current for tube 8, and in the absence of conduction current in tube 4, both -multicurrent in resistor I8 of aWave-forrn correspond` 70 vibrator circuits are returned to their initial ing to the rst half cycle in graph C. The voltage drop across resistor I8, due to said plate current in the said resistor, produces the Waveform shown in'graph E, for the period a-b, and this voltage reduces the output bias voltage ac- -starting conditions. Thus, a complete cycle of operation of the device for the letter d has been traversed.' In the general case, the periodfof the multi-vibrator 24 is slightly less than the sum 75 of the complete number of units in the code c'lrdinglyas@fshovvn` forfthemperiodedfb'h; thus regenerating -tl-ierspacingsignal..@father` through! lform foundin so'called Having fdes'cribed oneembodiln'ent of thein-IN vention,` the scope thereof is`set`forthv in the` claims hereunder. j f

unitsfof asingle by the whole-'period lengthv of the other of said electronic multi-vibrator circuits."rv f In the claims hereumler 4required to printa char? Y In 'a continuous distributor system, ve

the case of forth, aslwill be undertheart.

Squareewaves are defined r`to be tliejcommon WhatI'claiinis: l f" 1. In" an apparati'is `for"reg'enerating signal 'cur Y rents in anfequal-lunit-code input 'circuit'adapt'ed to'receive distorted -signal" currents inacode of equaleunits'atrandom'com binations, two electricallyY associated 4multi-vif- ]brator circuits, 'an'output L lcally associated,withlsaidoutput circuit for 'irin'gv under operation by vsaidrrandom 'combinations the period" of duration jof each of said units in 'said outputcircuit by the half-period'length of 'one ofv multi-vibrator circuits, and means said electronic for l'ixing the period ofthe sum of the total said operation in' said utputcircuit 2.`In an apparatus forr'regenerating currents representing'sig'nal characters in an equal-unitcode telegraph Ysystem over an outgoing line from signal currents;` received over an `"incoming 'line comprising, y-a'ninput' circuit to receivecode sig# i nals atirandom combinations, one electronic oscilthe jendo'f the. fourth unit andthe end lof theflfth unit,v and so l stood by those"V skilled in circuit, .means electri'- graph D, which pre- 'l Y posite polarity,said longimpulse having a period. *n I even. In a start-stop representing signal l5 a second jswitching period equal in lglflgthv Substantially to. v. that of all the character code-units combined, Y

pulse oi one polarity andonellongimpulse o f op- -equal substantially tothe length `of the sum of all lthe character code-units employed insaid code 20 coupling said telegraphsystemgan 5 signal currents received over an incoming' line an input circuit to receive c'ode signals Vat random combinations,lone electronicregenera` v op square-wave generator 1 of regenerated signal-wave-forms, a second eleclatoryfcircuit havingla period equal' to twice that of aV single unit length ofsaid code to regenerate the period oftheunitsj of said signals; a second electronic oscillatory circuit having' a period equal substantiallyV to the length of the sum-of all the units and fractions thereof in the code employed Y to regenerate the period of a'complete code-chate 50 ,code telegraph system overan outgoing line `from i:

received over yan incoming line acter operation, and'means electricallycoupling said two oscillatory circuits coordinating said14V periods. v f

3. Infan apparatus 'for regenerating currents A representing signal characters in anequal-unitcode telegraph system over an outgoing line from' signal.. currents received over an incoming linen comprising, an input circuit to receive code signals comprising,

"sinusoidal oscillator to :control th-period of the" first said-"svvit :hir`1'gjcircuit,V and means electrically two switching circuits coordinating?, saidperiois. I g y 5. Injan apparatus'for regenerating currents l representing signal charactersl in an 'equaleunit-l code telegraph system over an outgoing line from tive switching means to nx the'period of the dura-4 vtion of a single unit of said code, a second'elec'-V 6" tronic 'switching means to x'the number of uni/ts "1 employed in said code in a single operation there- 'i 5 of, and a f riod of the first said switching means;

6. In an apparatus for i code telegraph system over regenerating currents representing signal characters-'inv an equal-unite an'outgoing liine from` 'i signal currents received over an incoming-line* sinusoidaloscillator VtoV control the ipe# 5 combined, and means electrically` couplingsaid-` two oscillatory circuits coordinatingA said periods. 4. In an apparatus for regenerating currents characters inan equal-unit- Y code telegraphgsystem over an outgoing line from Y fl() signal currents received over an incomingline comprising, a`n input circuit to receive'codesig'nals at random combinations, one electronic regenera` j if tive switchingV4 circuit havinga switching period` f equal tojthe lengthof a single unity of said code,

electronic switching circuit having a comprising, an input circuit to receive code sigv nals at random combinations, one "electronic to provide output'currents l j tronic square-wave generator to` determine theV p cycle of operation of said system, andelectronic-g:

itube means electrically coupling said two generaj eration.

,i 17. In an apparatus forregeneratin'g currentsv Vrepresenting signal 'characters in an equal-unit# signal currents comprising,

combinations, one' squar'ewave alter- 43 Vtors coordinating said output currents of 'regen-Y Lerated signal-wave-forms with said cycleof opj hating-current velectronic generator to provideV Yforms, oneA electronic means .responsive to dis' torted input line currents providing signal tim- Y Y ing for said output currents, and a second squareatlrandom combinations-one electronic oscillatory circuit Vhaving a period @quai to. twice that of' a singleunit length of said code to regeneratethe period of the units of saidvsignals, aisecond electronicv oscillatory circuit Vhaving one vshort imwave alternating-current electronic generator cooperating 'electrically with,A iirst said generator determining the cycle ofv operation of said'system.V

currents of regenerated signal-'wave-r an input circuit to receive code signalsk 

